WASHINGTON — Boeing's KC-46 tanker marked a key milestone Sunday by successfully completing its first aerial refueling test.

During the Jan. 24 flight, the Boeing and US Air Force test team completed a series of test points with the aircraft before successfully transferring 1,600 pounds of fuel to an F-16 fighter jet, according to a company statement. The KC-46, a militarized version of the company's 767 commercial jet, took off from Boeing Field in Seattle, Washington.

During the 5 hour, 43 minute flight, the tanker's refueling "boom" – a rigid, telescoping tube that an operator on the aircraft extends and inserts into a receptacle on the receiving aircraft for fuel transfer – remained stable and performed well, the statement reads.

The test event kicks off the plane's "Milestone C" aerial refueling demonstration, required before beginning low-rate initial production.

"Today's flight is an important milestone for the Air Force/Boeing team," said Col. Christopher Coombs, Air Force KC-46 system program manager, according to the statement. "We have a lot of work yet to do, but this is an exciting time for the airmen who are preparing to fly, maintain and support the KC-46 Pegasus for decades to come."

Air Force fixed-wing assets use the boom system for aerial refueling, with a planned 1,200 gallons-per-minute transfer rate from the KC-46. Air Force helicopters and most Navy and Marine Corps aircraft, on the other hand, use the "probe-and-drogue" method of refueling. During this event, fuel passes from the tanker's "drogue" refueling basket, which trails from the plane via a flexible hose, through a "probe," a rigid, retractable arm placed on the receiver aircraft's nose or fuselage.

Yesterday's test event marks another sign the KC-46 program is on track after several setbacks in 2015. The test plane successfully completed first flight in September after it was initially planned for 2014.

In addition to repeated schedule delays, the program last year rang up an $835 million pre-tax charge stemming from developmental issues with the integrated fuel system on the plane. When combined with a $425 million pre-tax charge from a wiring issue in 2014, Boeing has racked up $1.2 billion overall in pre-tax overages on the program.

The Air Force is planning to buy 179 KC-46s in total to recapitalize its aging tanker fleet. According to the contract terms, Boeing must deliver 18 ready-to-go tankers by August 2017.

Email: lseligman@defensenews.com

Twitter: @laraseligman

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